Fixing inherited Sinclair ZX81
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Fixing inherited Sinclair ZX81
So the internal series regulators in the ULA are working (that generates a lot of the heat), but it looks like the clock / oscillator stages may not be working.
So yes, it’s dead unfortunately.
Mark
So yes, it’s dead unfortunately.
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: Fixing inherited Sinclair ZX81
Right, thank you. Sad as it is, this is positive news though. I now have a diagnosis and have therefore ordered a vLA81 and a socket.
I shall set to (carefully) desoldering the old ULA and will report back with my results once the vLA81 arrives and is installed.
Thank you again. I shall check in in a few days.
I shall set to (carefully) desoldering the old ULA and will report back with my results once the vLA81 arrives and is installed.
Thank you again. I shall check in in a few days.
Re: Fixing inherited Sinclair ZX81
Old ULA removed in readiness.
Re: Fixing inherited Sinclair ZX81
It’s alive! Thank you for all your help!
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Fixing inherited Sinclair ZX81
That’s good news
Mark
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: Fixing inherited Sinclair ZX81
Another one lives well done Mikeyp.
Add a switching reg to it and it will run a damn sight cooler and should last for ages.
Add a switching reg to it and it will run a damn sight cooler and should last for ages.
- 1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Fixing inherited Sinclair ZX81
I use Recom types (because I bought a load when the price was low), as detailed (and shown) in this topic. But other similar types like from Traco Power and MuRata are fine as well.
Mark
Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp
Standby alert
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Re: Fixing inherited Sinclair ZX81
Are not dangerous for the vLA81 using the RF?
Or is possible?
Thanks,
Matt
Or is possible?
Thanks,
Matt
Re: Fixing inherited Sinclair ZX81
Thanks, I'll see what I can find.
It shouldn't be a problem as the modulator only takes composite output and modulates it to RF. There's no mention of that on the website or manual. I configured mine to output the same as a 2C210E. I've had no issues with the display, modulator or the old black and white RF only TV I'm using.